Imidamides derived from 2-oxo-3-benzothiazoline acetic acid plant growth regulants

ABSTRACT

2-Oxo-3-benzothiazoleethanimidamides have been found to be effective in regulating the growth of leguminous plants.

This invention relates to the use of certainbenzothiazoleethanimidamides to regulate the growth of leguminousplants. More specifically, it relates to the regulation of leguminousplants, e.g., soybeans, by application of compounds having the formula##STR1## wherein T is halogen or trifluoromethyl, n is 0,1 or 2 and Y isoxygen or sulfur. Preferred are those compounds in which Y is oxygen, nis 0 or 1 and T is halogen.

The term "halogen" is understood to include chloro, fluoro, bromo andiodo.

The compounds of the foregoing formula may be prepared by reaction ofthe appropriate substituted acetonitrile and hydroxylamine hydrochloridein a suitable solvent in accordance with the following equation:##STR2##

Useful solvents include lower alcohols, e.g., those having up to fourcarbon atoms, tetrahydrofuran, dimethylformamide, dimethylsulfoxide andthe like.

Useful bases include ammonium hydroxide, alkali metal carbonates andalkali metal hydroxides, e.g., sodium and potassium hydroxide andtertiary amines.

The method of preparing the acetonitrile precursor is known and has beendisclosed in U.S. Pat. Nos. 4,049,419 and 3,993,468. Additionally,copending application Ser. No. 055,104 filed July 5, 1979, entitled"Derivatives Of 2-Thioxo-3-Benzothiazoline Acetonitrile And Their Use AsLeguminous Plant Growth Regulants" discloses the preparation of theacetonitrile precursors wherein Y is sulfur. To illustrate the aboveprocess for preparing the compounds of the invention the followingprocedure has been used:

A stirred slurry containing 0.1 mol of the appropriate substitutedacetonitrile in 700 to 900 ml of ethyl alcohol was heated to 60° C. andthen allowed to cool to room temperature. To this stirred mixture, asolution containing 7 g (0.1 mol) of hydroxylamine hydrochloride in 25ml of water was added in one portion and stirring continued at 25°-30°C. for six hours. A solution containing 6.4 g (0.06 mol) of potassiumcarbonate in 25 ml of water was added and stirring continued at 25°-30°C. for 18 hours. After the addition of 500 to 1000 ml of water, stirringwas continued at 25°-30° C. for 30 minutes. The solid was collected byfiltration, washed with water until neutral and air-dried at 25°-30° C.The data is summarized in Table I.

                                      TABLE I                                     __________________________________________________________________________     ##STR3##                                                                     Example                                                                            CP       m.p.                                                                              %   % C     % H     % N     % S                             No.  No. T  Y °C.                                                                        Yield                                                                             Calc'd                                                                            Found                                                                             Calc'd                                                                            Found                                                                             Calc'd                                                                            Found                                                                             Calc'd                                                                            Found                       __________________________________________________________________________    1        H  O 202-3.sup.a                                                                       90  48.42                                                                             48.36                                                                             4.86                                                                              4.06                                                                              18.82                                                                             18.82                                                                             14.36                                                                             14.34                       2        5-Cl                                                                             0 222-3                                                                             87  41.95                                                                             41.98                                                                             3.13                                                                              3.16                                                                              16.31                                                                             16.30                                                                             12.44                                                                             12.46                       3        6-Br                                                                             O 216-7.sup.b                                                                       80  35.78                                                                             35.75                                                                             2.67                                                                              2.68                                                                              13.91                                                                             13.91                                                                             10.61                                                                             10.65                       4        H  S 191-2.sup.c                                                                       86  45.17                                                                             45.19                                                                             3.79                                                                              3.83                                                                              17.56                                                                             17.52                                                                             26.80                                                                             26.77                       __________________________________________________________________________     .sup.a Recrystallization from isopropyl alcohol/DMF (1:1)                     .sup.b Recrystallization from DMF                                             .sup.c Recrystallization from ethyl acetate                              

In accordance with the novel aspects of the present invention, thecompounds of the foregoing formula are effective plant growth regulants,especially in the regulation of leguminous plants.

The term "plant regulant" or "plant growth regulant", as employed inthis application, connotes a material which serves to modify the normalsequential development of a treated plant to agricultural maturity. Suchmodification may result from the effect of material on the physiologicalprocesses of the plant or from the effect of said material on themorphology of the plant. It should additionally be recognized thatmodifications may also result from a combination or sequence of bothphysiological and morphological factors.

Modifying effects of a plant regulant are probably most readily observedas changes in the size, shape, color or texture of the treated plant orany of its parts. Similarly, changes in the quantity of the plant fruitor flowers are also quite apparent from simple, visual inspection. Theabove changes may be characterized as an acceleration or retardation ofplant growth, such as an increase or decrease in dry weightaccumulation, stature reduction, leaf or canopy alteration, increasedbranching, terminal inhibition, increased flowering or fruit set.

Modifications in the normal sequential development of a treated plant toagricultural maturity may also be manifested by reduced transpiration orincreased carbohydrate deposition or protein content.

It is to be understood that each response may occur in conjunction withother responses, but may occur separately. For example, depending uponvarious factors realized by those skilled in the art to effect activity,the data illustrated below demonstrates that the compounds of thepresent invention sometimes alter the leaf morphology even though theplants are not reduced in stature.

The regulation of plants in accordance with the instant invention doesnot include the total inhibition or the killing of such plants. Althoughphytotoxic amounts of the materials disclosed herein might be employedto exert a herbicidal (killing) action, it is contemplated herein toemploy only plant regulating amounts of such materials in order tomodify the normal sequential development of the treated plant toagricultural maturity. The application of a plant regulating amount maybe applied to plants in sequence at various stages of the plants'development to obtain various desirable responses. As may be expected,and as is apparent to those skilled in the art, such plant regulatingamount will vary, not only with the material selected, but also with themodifying effect desired, the species of plant and its stage ofdevelopment, the plant growth medium and whether a permanent ortransitory effect is sought.

To illustrate the variety of regulatory responses observed, thecompounds of the invention were tested in accordance with the followingprocedure.

A number of soybean plants are grown from seeds in plastic pots in thegreenhouse for a period of one week at which time the plants are thinnedto one plant per pot. When the second trifoliate leaf is fully expanded,the plants are treated with a solution of the active ingredient inacetone and water. Aqueous Tween 20 is used as a surfactant.

When the fifth trifoliate leaf of the control is fully expanded, thetreated plants are compared with the non-treated control plants and theobservations recorded.

The following observations were made when soybeans were treated at theindicated rates with the compounds of the foregoing formula.

    ______________________________________                                        Compound of                                                                            Rate                                                                 Example No.                                                                            (kg/ha)    Observations                                              ______________________________________                                        1        0.112      leaf alteration of new                                                        growth, inhibition of dry                                                     weight                                                             0.56       leaf alteration of new                                                        growth, leaf inhibition                                            2.8        leaf alteration of old and                                                    new growth, leaf inhibition,                                                  altered canopy, chlorosis,                                                    inhibition of dry weight                                  2        0.112      inhibition of dry weight                                           0.56       leaf alteration of new                                                        growth, inhibition of dry                                                     weight                                                             2.8        leaf alteration of new growth,                                                inhibition of dry weight                                  4        0.112      none                                                               0.56       leaf alteration of new growth,                                                leaf inhibition                                                    2.8        stature reduction, leaf                                                       alteration of old and new                                                     growth, leaf inhibition                                   ______________________________________                                    

From the above data, it can be seen that the compounds of the presentinvention are especially effective in altering the leaf morphology ofsoybean plants.

Alteration of the leaf morphology of leguminous plants is importantbecause leguminous plants have canopies that effectively inhibitsunlight from reaching the lower leaves. For example, only about 50% ofa soybean plant's leaves intercept light for photosynthesis.Approximately 85% of the light is absorbed by the outer layer of leaves.Many researchers feel that by altering the morphology of the leaves suchthat the canopy is altered, light may fall more deeply into the canopy,and yields could be increased. Weber, in "Field Crop Abstracts", Volume21, No. 4, pages 313-317, states that "greater light penetration,resulting in greater amount of the [soybean] plant canopy having a lightintensity above 150 f.c., generally led to higher seed yields". Johnsonet al, in "Crop Science", Volume 9, pages 577-581, states that "addinglight increased the yields of bottom, middle and top canopy positions of[soybean] plants 30, 20 and 2% respectively." Thus, it would be highlybeneficial if a method was found whereby the leaves of such plants couldbe altered such that a greater number of leaves could be illuminated.

In practicing the plant growth regulating methods of this invention, theactive ingredient can be used alone or in combination with a materialreferred to in the art as an adjuvant in liquid or solid form. The plantgrowth regulating compositions of this invention are prepared byadmixing the active ingredient with an adjuvant including diluents,extenders, carriers and conditioning agents to provide compositions inthe form of finely-divided particulate solids, granules, pellets,wettable powders, dusts, solutions and aqueous dispersions or emulsions.Thus, the active ingredient can be used with an adjuvant such as afinely-divided particulate solid, a solvent liquid of organic origin,water, a wetting agent, dispersing agent, or emulsifying agent or anysuitable combination of these.

When applying the active ingredient to leguminous plants, useful finelydivided solid carriers and extenders include, for example, the talcs,clays, pumice, silica, diatomaceous earth, quartz, Fullers earth,sulfur, powdered cork, powdered wood, walnut flour, chalk, tobacco dust,charcoal and the like. Typical liquid diluents useful in applying theactive ingredient to leguminous plants include, for example, Stoddardsolvent, acetone, alcohols, glycols, ethyl acetate, benzene and thelike. Such leguminous plant growth regulating compositions, particularlyliquids and wettable powders, usually contain as a conditioning agentone or more surface-active agents in amounts sufficient to render agiven composition readily dispersible in water or in oil. By the term"surface-active agent", it is understood that wetting agents, dispersingagents, suspending agents and emulsifying agents are included therein.Such surface-active agents are well known and reference is made to U.S.Pat. No. 2,547,724, columns 3 and 4, for detailed examples of the same.

Compositions of this invention generally contain from about 5 to 95parts active ingredient, about 1 to 50 parts surface-active agent andabout 4 to 94 parts solvent, all parts being by weight based on thetotal weight of the composition.

Desirable modification of leguminous plants may be achieved by applyingthe above-described plant regulants to the plant locus. The term "plantlocus" is understood herein to include the plant growing medium, such asthe soil, as well as the seeds, emerging seedlings, roots, stems,leaves, flowers, fruits or other plant parts.

The application of liquid and particulate solid compositions of theactive ingredient can be carried out by conventional techniquesutilizing, for example, spreaders, power dusters, boom and hand sprayersand spray dusters. The compositions can also be applied from airplanesas a dust or spray. If desired, application of the compositions of theinvention to leguminous plants can be accomplished by incorporating thecompositions in the soil or other media in the area where modificationof the plants is desired.

In selecting the appropriate non-toxic rate of application of the activeingredient to leguminous plants, it will be recognized that preciserates will also be dependent upon the mode of application, such as soilincorporation, band application, pre-plant seed treatment, resultdesired and various other factors known to those skilled in the art. Inapplications to the soil habitat of germinant seeds, emerging seedlings,and established vegetation for the regulation of plant growth, theactive ingredients are applied in amounts of from about 0.056 to 22.4kilos/hectare. Foliar application is particularly advantageous and ispreferred especially from about 0.112 to about 3.36 kilos/hectare.

Although this invention has been described with respect to specificmodifications, the details thereof are not to be construed aslimitations, for it will be apparent that various equivalents, changesand modifications may be resorted to without departing from the spiritand scope thereof and it is understood that such equivalent embodimentsare intended to be included herein.

We claim:
 1. A method of regulating the growth of leguminous plantswhich comprises applying to the plant locus a plant growth regulatingeffective amount of a compound having the formula ##STR4## wherein T ishalogen or trifluoromethyl, n is 0,1 or 2 and Y is oxygen or sulfur. 2.A method according to claim 1 wherein Y is oxygen.
 3. A method accordingto claim 2 wherein n is
 0. 4. A method according to claim 1 wherein n is0.
 5. A method according to claim 1 wherein Y is sulfur.
 6. A methodaccording to claim 5 wherein n is
 0. 7. A method according to claim 1wherein T is halogen and n is
 1. 8. A composition for regulating thegrowth of leguminous plants which comprises from about 5 to 95 parts byweight of a compound having the formula ##STR5## wherein T is halogen ortrifluoromethyl, n is 0, 1 or 2 and Y is oxygen or sulfur; the remainingparts being comprised of 1 or more suitable adjuvants, diluents orcarriers.
 9. A composition according to claim 8 wherein Y is oxygen. 10.A composition according to claim 9 wherein n is
 0. 11. A compositionaccording to claim 8 wherein n is
 0. 12. A composition according toclaim 8 wherein Y is sulfur.
 13. A composition according to claim 12wherein n is
 0. 14. A composition according to claim 8 wherein T ishalogen and n is 1.